Suggestion for Increasing Durability[edit source]
You may find a solution to corosion by treating the evaporating pan(metal) in a manner similar to coating cast iron cookware.I recommend a heavy and/or repeated coating of the evaporator pan by heating it first to between 400-500 degrees Fahrenheit in order to sublimate a cooking oil. I Have steel baking pans treated with a heavy coating safflower oil baked at 450F* for an hour, and that was years ago. Despite soaking, scrubbing and dishwasher treatment they still haven't rusted.